Change the way of mouse click on task bar in Windows 7. By default, left click on task bar, it pops up the preview windows. This can be change to what it likes in Windows XP. Left click on task bar to bring up the last active windows.
This is the registry need to be changed.
Windows Registry Editor Version 5.00
Open notepad, and copy and paste the code, save it to LastActiveClick.reg, double click LastActiveClick.reg, accept the change, log off and log in again.